Pennsylvania Gov. Tom Corbett, who’s suffering from low approval ratings and has a tough reelection battle looming next year, is facing yet another politically difficult decision: whether or not to stand up for the Keystone State’s same-sex marriage ban.

State Attorney General Kathleen Kane, a Democrat, said Thursday that she wouldn’t defend the ban in court — raising the issue on a state level for the first time since the Supreme Court ruled against the federal Defense of Marriage Act.

The American Civil Liberties Union filed the first known legal challenge to Pennsylvania’s Defense of Marriage Act in Harrisburg earlier this week, naming Corbett, Kane and three other state officials as defendants. The suit argues that Pennsylvania’s law violates a fundamental right to marry and also goes against the Constitution’s equal protection clause.

Since Kane has declined to defend the law, the responsibility falls to Corbett to decide what to do. Pennsylvania General Counsel James D. Schultz said in a statement Thursday afternoon that Corbett’s office “will continue to review the lawsuit” — and took a swipe at Kane.

“We are surprised that the Attorney General, contrary to her constitutional duty under the Commonwealth Attorneys Act, has decided not to defend a Pennsylvania statute lawfully enacted by the General Assembly, merely because of her personal beliefs,” Schultz said.

Corbett faces a rock-and-hard place decision. If he opts to defend the law — he’s expressed support for it in the past — Corbett will draw ire from a Democratic base that already despises him. If he chooses not to defend it, he risks alienating the members of his own party he needs for reelection next year.

“Corbett will defend [the law],” said Franklin & Marshall pollster Terry Madonna. “He opposes gay marriage and his conservative base would be furious with him if he does not.”

On the other hand, the suit over the state’s same-sex marriage ban comes at a time when Pennsylvania public opinion on the issue has seen a major shift. A Franklin & Marshall poll from earlier this year found 52 percent of registered voters support same-sex marriage, while 41 percent oppose it.

By defending the law, said Muhlenberg College pollster Chris Borick, Corbett would be “going counter to general public opinion in the state — but he has to worry first about his very lukewarm support within his own party.”

GOP strategist Ray Zaborney said he doesn’t think the issue “cuts one way or another” in the state. But Zaborney said Democrats are certain to attack the governor if he defends the law.

“I think some Democrats will certainly try to use it against the governor just like conservative Republicans would use it against him if he didn’t,” he said.

Corbett, first elected in the GOP wave of 2010, has seen his approval ratings stuck in the low 30s and even 20s, and trails his potential Democratic challengers in most recent polls of the race. The Democratic primary will likely be crowded, with Rep. Allyson Schwartz looking like the likely frontrunner so far.

Borick noted that the electorate in a lower-turnout midterm year like 2014, when Corbett is facing reelection, skews older and more Republican, so the types of voters who will turn up at the polls next year are more evenly split on the issue.

“When you start to look at who shows up in a midterm election like 2014, you’re looking a little bit of a different audience and the issue is more divided,” he said.